help please, jst getting started

I have just replaced an ACME feed screw with a ball-screw on a Harrison milling machine, and in the process have had to remove the table feed motor.
A number of people have fitted NEMA hybrid servo motors as part of a CNC conversion. What I would like to do is retain a manual control along with a DRO readout but I am struggling to find information on how I can do this.

At the moment I have the original hand-wheel driving the screw directly. What I would like to be able to do eventually is to fit a stepper motor with a view to full CNC control and fit a rotary encoder to drive it manually. The only problem with this is I would have no idea of the cutter position.
Can I attach a DRO to the stepper driver and get a digital readout of the tool position? or do I have to fit scales?
If I have to fit scales can I use the position from the scales to drive the stepper motors position, and use a non hybrid stepper. If I use a hybrid stepper how do i account for any lost steps?

I have tried searching the forum but keep getting no results, so I am probably asking the wrong questions.